/*
silverPDF is sponsored by Aleyant Systems (http://www.aleyant.com)

silverPDF is based on PdfSharp (http://www.pdfsharp.net) and iTextSharp (http://itextsharp.sourceforge.net)

Developers: Ai_boy (aka Oleksii Okhrymenko)

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:

The above information and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR SPONSORS
BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.

*/
#region PDFsharp - A .NET library for processing PDF
//
// Authors:
//   Stefan Lange (mailto:Stefan.Lange@pdfsharp.com)
//
// Copyright (c) 2005-2008 empira Software GmbH, Cologne (Germany)
//
// http://www.pdfsharp.com
// http://sourceforge.net/projects/pdfsharp
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
// DEALINGS IN THE SOFTWARE.
#endregion

using System;
using System.Diagnostics;
using System.Collections;
using System.Text;
using System.IO;
#if GDI
using System.Drawing;
using System.Drawing.Imaging;
#endif
#if WPF
using System.Windows.Media;
#endif
using PdfSharp.Drawing;
using PdfSharp.Fonts.TrueType;
using PdfSharp.Internal;

namespace PdfSharp.Pdf.Advanced
{
  /// <summary>
  /// Represents a PDF soft mask.
  /// </summary>
  public class PdfSoftMask : PdfDictionary
  {
    /// <summary>
    /// Initializes a new instance of the <see cref="PdfXObject"/> class.
    /// </summary>
    /// <param name="document">The document that owns the object.</param>
    public PdfSoftMask(PdfDocument document)
      : base(document)
    {
      Elements.SetName(Keys.Type, "/Mask");
    }

    /// <summary>
    /// Predefined keys of this dictionary.
    /// </summary>
    public class Keys : KeysBase
    {
      /// <summary>
      /// (Optional) The type of PDF object that this dictionary describes;
      /// if present, must be Mask for a soft-mask dictionary.
      /// </summary>
      [KeyInfo(KeyType.Name | KeyType.Optional, FixedValue = "Mask")]
      public const string Type = "/Type";

      /// <summary>
      /// (Required) A subtype specifying the method to be used in deriving the mask values
      /// from the transparency group specified by the G entry:
      /// Alpha: Use the group�s computed alpha, disregarding its color.
      /// Luminosity: Convert the group�s computed color to a single-component luminosity value.
      /// </summary>
      [KeyInfo(KeyType.Name | KeyType.Required)]
      public const string S = "/S";

      /// <summary>
      /// (Required) A transparency group XObject to be used as the source of alpha
      /// or color values for deriving the mask. If the subtype S is Luminosity, the
      /// group attributes dictionary must contain a CS entry defining the color space
      /// in which the compositing computation is to be performed.
      /// </summary>
      [KeyInfo(KeyType.Stream | KeyType.Required)]
      public const string G = "/G";

      /// <summary>
      /// (Optional) An array of component values specifying the color to be used
      /// as the backdrop against which to composite the transparency group XObject G.
      /// This entry is consulted only if the subtype S is Luminosity. The array consists of
      /// n numbers, where n is the number of components in the color space specified
      /// by the CS entry in the group attributes dictionary.
      /// Default value: the color space�s initial value, representing black.
      /// </summary>
      [KeyInfo(KeyType.Array | KeyType.Optional)]
      public const string BC = "/BC";

      /// <summary>
      /// (Optional) A function object specifying the transfer function to be used in
      /// deriving the mask values. The function accepts one input, the computed
      /// group alpha or luminosity (depending on the value of the subtype S), and
      /// returns one output, the resulting mask value. Both the input and output
      /// must be in the range 0.0 to 1.0; if the computed output falls outside this
      /// range, it is forced to the nearest valid value. The name Identity may be
      /// specified in place of a function object to designate the identity function.
      /// Default value: Identity.
      /// </summary>
      [KeyInfo(KeyType.FunctionOrName | KeyType.Optional)]
      public const string TR = "/TR";
    }
  }
}